A house extension can transform your home, adding valuable living space. Costs cover foundations, structural work, roofing, glazing, internal fit-out, and connection to existing services. In Clapham (SW4, SW11), costs reflect the area's Inner London market position, with a 5% premium over London averages.
Clapham is one of South London's most popular areas, centred around the beautiful Common. It features Georgian houses along the Common, Victorian terraces in side streets, and a vibrant high street.
| Specification | Price per sqm | Typical 25sqm Project | Includes |
|---|---|---|---|
|
Standard
Quality materials, clean design
|
£2,625 – £3,360 | £65,625 – £84,000 | All structural work, standard fixtures, full fit-out and decoration |
|
Premium
Designer brands, bespoke elements
|
£3,360 – £4,200 | £84,000 – £105,000 | Premium materials, designer fixtures, underfloor heating, smart controls |
|
Luxury
Finest materials, fully bespoke
|
£4,200 – £5,775 | £105,000 – £144,375 | Bespoke joinery, natural stone, top-tier appliances, architectural detailing |
Prices include VAT and are based on Clapham (SW4, SW11) market rates. Prices reflect Inner London market conditions and local construction costs. Actual costs depend on site-specific factors. All prices are guide estimates for 2025.
Here's what a typical 25sqm house extension project would cost in Clapham at each specification level.
Clapham Common and Old Town Conservation Areas protect the Georgian and early Victorian character. Properties on the Common have particularly strict controls.
Key streets and roads in Clapham include Clapham Common North Side, Old Town, The Pavement, Crescent Lane, Narbonne Avenue. Properties in these locations often have specific architectural characteristics that influence renovation costs, including Georgian property restoration expertise needed for Common-fronting houses, Victorian terrace efficiencies for side-street properties, good transport for material delivery.
Every house extension is unique. Let our RIBA chartered architects provide a detailed, no-obligation estimate tailored to your property and specification.
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